Valve-operating mechanism for internal-combustion engines



July 7, 1925.

J. G. P. THOMAS VALVE ornnxrme MECHANISM FOR INTERNAL comaus'nou Emmms Iii) Patented uly 7, 1925.

UNITED STATES rem: ear. moms, or LONDON, ENGLAND.

VALVE-OPERATING MECHANISM FOR INTERNAL-COMBUSTION ENGINES.

Application filed February 20, 1824. Serial No.'894,153.

To aZZ whom it may concern:

Be it known that 1, JOHN Gonrnnx PARRY THOMASLE. subject of the King of Great Britain and Ireland, residing at 29 Spring Gardens, London, S. W. 1, England, have invented new and useful Valve-Operating Mechanism for .Internal-Combustion Engines, of which the following is a specification.

Ihis invention relates to mechanism for operating the valves of internal combustion engines. Its purpose is to provide for the rapid operation of the valves of high-speed engines, so that the speed attainable and the power which can be developed by one cylinder may not be limited as in many existlng engines by the relative slowness of movement of the valves.

It is important to reduce the mass of the valves, and the mass and extent of movement of all the moving parts of the valve operating mechanism as much It is also important to effect the movement of the valves in both directions, that is to say both in opening and in closing, positively, instead of relyingas usual -upon a spring to return the valves to their seating; while nevertheless resilient means are desirable for retaining the valve on its seatlhe invention particularly relates to the combination with the inlet and outlet valve in a cylinder head of rocking levers and cams for opening saidvalve, and a common spring bearing upon said valves and upon an intermediate abutment and tending to close the valves; and it contemplates the substitution for the common spring in such a combination of a substantially rigid lever having resilient means interposed between it and each of the valves. It also includes the provision of means for reciprocating the intermediate abutment in such a combination to effect the positive closure of the valves.

Other combinations and developments forming part of the invention will be found described hereinafter and set forth in the I appended claims.

By way of example the invention is explained in detail with reference to the embodiment illustrated in the accompanying drawing, which is a sectional elevation of the head and valve operating mechanism of one cylinder of an internal combustion engine, which may and usually will be a multi-cylinder engine.

as possible.

While the invention is applicable to internal combustion engines generally it is illustrated as applied to an engine having an overhead cam shaft. In the drawing only a part of a single cylinder 1 is shown, but it will be understood that the engine will usually be a multi-cylinder engine. In the head 2 are inlet and exhaust valves 3, 4, held upon their seatings by a lever or laminated spring 5, which bears on the one hand upon cotter pins 6, 7, in the valve stems, and on the other hand against an abutment 8. The valves are opened by rocking levers 9, 1O actuated by a common cam 11 on the overhead cam shaft 12.

For the purpose of the invention the abutment 8 is made movable, for instance, as shown, slidable in a -guide 13; and it is oscillated in correspondence with the movements of the levers 9, 10 by a cam 14 on an auxiliary cam shaft 15.

as to allow the spring abutment 8 tofall twice during each revolution, namely at the times when the cam lfZ'is o crating lever 9 and lever 10 respectively. etween those times the cam 14 closes the valves by liftim the abutment 8.

by suitable design of the profile of the cams 12 and l-t variation in the stress on the member 5 may be substantially avoided. The member need not, therefore, be a spring of many laminations, but may have quite thick leaves, or may even be replaced by a very slightly yielding lever. The member ought always to exert some stress tokeep the valves firmly on their s'eatin when closed; and generally the cam 14: W11]. be so shaped as to close the valve slightly before its part of maximum diameter contacts with the abutment upon it, the remaining motion serving to stress the lever to give a tight closure. i

In the drawing the lever 5 is shown for this purpose as consisting of a' thick and therefore stiff central leaf with a thinner resilient leaf 16 above it. When the lever is unstressed the extreme end of the leaf 16 bearing upon the cotter pin 6 stands up a little above the forked end of the central leaf. Under inertia forces the end of spring 16 yields, and the valve is therefore positivel accelerated and brought to its seating y the substantially rigid central lamination. It is pressed and held upon its seating by the resilience of the leaf 16.

It will be seen that the cam 14 is so shaped What I claim is: 1. In an internal combustion engine the combination with a pair of valves in a cylinder head, of a lever engaging both of said valves to close them, an abutment for said lever intermediate said valves, a rocking lever for each valve operating to open the valve, and cam means for rocking said rocking levers and oscillating said abutment 2. In an internal combustion engine the combination with a pair of valves in a cylinder head, of a lever comprising a rigid portion adapted to engage said valves to close them and a yielding portion interposed between the valves and said rigid portion, an abutment for said lever intermediate said valves, rocking levers one for each Valve.

close them, an abutment for said lever,

means for? reciprocating said abutment to permit opening of said valves, and means for opening said valves in sequence. 1

4. in an internal combustion engine the combination with two valves in the cylinder head, of a guide located between said valves, a plunger sliding in said guide, a cam acting upon said plunger to reciprocate it, and a lever engaged with said valves to close them and resting on said plunger.

5. In an internal combustion engine the combination with two valves in the cylinder head, of two cam shafts above the cylinder head, cams on each of said shafts, rocking levers rocked by a cam on the one shaft engaging said valves to open them, an abutment reciprocated by a cam on the other shaft, and a resilient lever pressing upon said valves to close them and upon said abutment.

In testimony'wheieof l have signed my name to this specification.

J G. P, THOMAS. 

